Abstract

The state of the molecule was reinvestigated with different techniques at two synchrotron installations. The Fourier transformspectrometer in the vacuum ultraviolet wavelength range of the DESIRS beamline at the SOLEIL synchrotron was used for recording absorption spectra of the state at high resolution and high absolute accuracy, limited only by the Doppler contribution at 100 K. From these measurements, line positions were extracted, in particular, for the narrow resonances involving states, with an accuracy estimated at . The new data also closely match multichannel quantum defect calculations performed for the components observed via the narrow Q-lines. The -doubling in the state was determined up to . The 10 m normal incidence scanning monochromator at the beamline U125/2 of the BESSY II synchrotron, combined with a home-built target chamber and equipped with a variety of detectors, was used to unravel information on ionization, dissociation, and intramolecular fluorescence decay for the vibrational series. The combined results yield accurate information on the characteristic Beutler–Fano profiles associated with the strongly predissociated parity components of the levels. Values for the parameters describing the predissociation width as well as the Fano- line shape parameters for the and rotational states were determined for the sequence of vibrational quantum numbers up to .

Received 27 July 2010Accepted 26 September 2010Published online 14 October 2010Corrected 02 December 2010

Acknowledgments:

The staff of SOLEIL and its DESIRS beamline is thanked for the support and for providing the opportunity to conduct measurements in the campaigns in 2009. This work was supported by the Netherlands Foundation for Fundamental Research of Matter (FOM). We are indebted to EU for its financial support via the Transnational Access funding scheme. M.G.M. acknowledges help from P. Reiss, H. Schmoranzer, and the BESSY staff, and is indebted to EU for the support (Grant ELISA No. 226716). W.-Ü.L.T.B. is indebted to the French ANR project SUMOSTAI for the support.